Styrene copolymers combined with metallic species in deposition inhibition

ABSTRACT

Provided herein are compositions useful for inhibiting the formation of gummy residues on equipment in processing operations which liberate tiny adhesive particles having a tendency to agglomerate into larger particles and/or films. The compositions comprise a complex or adduct formed from styrene/methacrylic acid copolymer and calcium ions. The compositions according to the invention may be added to a processing system at any point, either upstream or downstream from the location at which residues are formed. Compositions according to the invention may be applied by spray techniques.

[0001] This invention relates to compositions of matter useful in causing tacky surfaces or materials to be rendered less tacky. More particularly, the invention relates to compositions useful in preventing coagulation in solutions comprising minute particles of tacky materials. The compositions and processes detailed herein are especially well-suited for use in paper mills and other employments where solutions containing sticky particles come into contact with process equipment and have the propensity to cause fouling of the surfaces of such equipment by agglomeration of such particles.

BACKGROUND

[0002] The formation of troublesome agglomerations of sticky bodies in aqueous solutions used in processing various chemical materials has been observed in various systems for some time. Such formation is a particular noteworthy problem in the paper and pulp manufacturing industry, regardless of the method used to pulp raw wood.

[0003] In general terms, there are two methods which are recognized by those in the paper science arts for making a pulp from which many useful products may be derived. The qualities of the pulp produced by each process renders them each useful in particular end-use applications.

[0004] The first of such processes is a chemical process, which is known as the “kraft” process, and involves chemically treating wood chips and the like at an elevated temperature with a strongly alkaline aqueous solution of sodium sulfide in order to produce a pulp having most of the lignins and resins removed from the interstices between the individual fibers.

[0005] The second of such processes is known as mechanical pulping and entails forcing de-barked logs against a grinding stone or metal disks called “refiners” in order to produce a pulp. From the mechanical process is produced a pulp product having more of the lignins and the resins remaining in the pulp than in the kraft process. There are other processes employed for pulping, which contain some character of each of the chemical and the mechanical processes. In one variant, wood chips are treated with steam in the presence of caustic soda for a prescribed time prior to being subject to grinding in the mechanical process. In another variant, wood chips are impregnated with sulfur compounds prior to the steaming.

[0006] Regardless of the method used to produce a pulp, all pulping processes are carried out in the presence of water, which is capable of acting as a carrier for all of the materials present during the pulping. Some of the materials include as aforesaid, the resins and lignins, which are capable of existing in the form of soaps. One particularly troublesome property of these materials is that while soluble at high pH levels, they tend to exist in the form of particulate precipitates in the presence of divalent metal ions, such as the alkaline earth metals. The nature of these particulate precipitates is that they are generally very sticky on their exterior and thus have a propensity towards formation of larger gummy globules and/or films on equipment with which they come into contact. This problem is typically manifest at the point at which the soluble resin and lignin first come into contact with a source of di-valent metal cation, which in the case of the chemical process is usually in the first washer which the pulp encounters after leaving the digesters because this is where fresh rinse water containing di-valent metal ions enters such a chemical pulping system. The initial deposition of such particles is often in the form of a rough film. As deposition continues, thick incrustations form, particularly on exposed edges to such an extent as to interfere with the operation of the pulp mill equipment. Eventually, portions of, or even the whole operation must be shut down to enable cleaning of the machinery, which is a costly and time-consuming endeavor.

[0007] Another class of materials known as “stickies” are troublesome in pulping and like operations. Whereas pitch, resin, and the like arises from the processing of virgin pulp, stickies arise from secondary fibers. Stickies are described in U.S. Pat. No. 4,956,051 which is incorporated in its entirety herein by reference thereto.

[0008] The prior art is replete with the attempts of various workers to prolong or even eliminate the formation of such deposits on paper mill equipment. For example, U.S. Pat. No. 3,992,249 which is incorporated herein in its entirety by reference thereto, teaches a process for inhibiting the deposition of adhesive pitch particles onto the surface of pulp-making equipment, prior to beating, from the water with which a cellulose fiber suspension having a content of the particles is being washed. The process comprises washing the suspension in a pulp washer containing an aqueous solution of an anionic polymer containing at least about 25 mol percent, but not more than about 85 mol percent, of hydrophobic-oleophilic linkages. Hydrophobic oleophilic linkages suitable for this employment are selected from the group comprising styrene, isobutylene, methylstyrene, allyl stearate, octadecyl acrylate, octadecene, dodecene, n-octadecylacrylamide, vinyl stearate and vinyl dodecyl ether. Also present in the solution is at least about 15 mol percent, but not more than about 75 mol percent, of hydrophilic acid linkages. Hydrophilic acid linkages suitable for this use are selected from the group comprising acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamidoacetic acid, maleamic acid and styrenesulfonic acid. A pitch-polymer complex of the particles and the polymer is formed by their admixture, which is removed with the water used to wash the cellulose fiber suspension. Thus, substantially all of the pitch-polymer complex is separated from the cellulose fiber suspension. The amount of the polymer used is in the range of about 0.5 to 100 parts by weight per million parts by weight of the suspension.

[0009] U.S. Pat. No. 4,184,912 which is incorporated herein in its entirety by reference thereto, teaches a method of inhibiting pitch formation in paper mill pulp systems which comprises adding to such systems, at a point prior to where pitch deposits normally occur, at least 0.5 ppm, based on the weight of the pulp, of a composition comprising varying amounts of surfactants. One such system contains varied amounts of: Non-ionic surfactant; Anionic Dispersant; Anionic Polymer having molecular weight less than 100,000. In another embodiment, the surfactants comprise: an ethoxylated phenol; an alkyl-substituted naphthalene sulfonate; and an acrylic acid co-polymer (molecular weight between 5,000 and 40,000).

[0010] U.S. Pat. No. 6,143,800 which is incorporated herein in its entirety by reference thereto, discloses compositions and methods for inhibiting deposition of organic contaminants in equipment associated with a pulping operation which entails the addition of a composition comprising: a dinonyl sulfosuccinate anionic surfactant; and a multivalent cation to the system wherein the weight ratio of said dinonyl sulfosuccinate anionic surfactant to multivalent cation ranges from about 1:4 to about 1:100. A composition embraced by the above-mentioned description is added to the pulp or the surfaces of pulping mill machinery in an effective deposition inhibiting amount.

[0011] However, each of the methods of the prior art has its own drawbacks. For example, the teachings of U.S. Pat. No. 3,992,249 uses calcium to form pitch and subsequently adds a sodium salt copolymer to prevent further deposition of unwanted solids such as pitch, stickies, and the like. U.S. Pat. No. 4,184,912 and 6,143,800 claim the use of surfactants to control the deposition of stickies, pitch, and the like, but when the fiber slurry is diluted with white water from the paper-making machinery the surfactants tend to de-sorb from the surfaces of the stickies, pitch, and like particles. As a result the particles once again become susceptible to agglomeration with themselves and other particles, and are hence once again susceptible to re-deposition.

SUMMARY OF THE INVENTION

[0012] The present invention provides an aqueous composition of matter which comprises a copolymer component comprising a water soluble anionic form of styrene/methacrylic acid copolymer and a metal component. The copolymer preferably has a styrene content in the range of about 10.0% to about 45.0% by weight based upon its total weight, and has a molecular weight in the range of about 1,000 to about 100,000. The metal component comprises an aqueous solution containing at least one multivalent cation selected from the group consisting of: calcium, magnesium, strontium, barium, nickel, copper, tin, cobalt, iron, zinc, or mixtures thereof. The ratio of the copolymer component to the metal component is in the range of between 1:4 to 1:500 on a weight basis.

[0013] In order to use a composition according to the invention, one introduces an effective deposition inhibiting amount of said aqueous composition into a process stream in which pitch, resin, lignin, and other residues exist or are liberated. The concentration of the copolymer component in an aqueous composition according to the invention in the process stream is in the range of between about 0.5 parts per million to 500 parts per million by weight based upon the weight of the process stream. The metal component content in a composition according to the invention is calculated based upon the amount of copolymer present. One preferred form of the invention employs a copolymer component concentration of between about 10 ppm to 50 ppm based upon the amount (weight basis) of the process stream treated and the metal component is calcium ion, present at between about 100 ppm to 500 ppm, also based upon the amount (weight basis) of the process stream treated.

DETAILED DESCRIPTION

[0014] The present invention provides a composition of matter which comprises at least one styrene/methacrylic acid copolymer in combination with a multi-valent metal cation, which compositions according to the invention are preferably aqueous solutions comprising these components. To provide a composition according to the invention, one first provides the copolymer component as an aqueous solution of its alkali metal salt. Suitable metals include lithium, sodium, potassium, rubidium, etc. A preferred ratio of styrene to methacrylic acid in the copolymer is 40:60 on a weight basis; however, copolymers having any content of styrene in the range of 10.0% to 45.0%, by weight based upon the total weight of the styrene/methacrylic acid polymer, including every hundredth percentage therebetween, are suitable for use in the present invention.

[0015] Styrene/Methacrylic Acid Copolymer and Water Soluble Salt Thereof

[0016] The preparation of styrene/methacrylic acid copolymers is straightforward and is known in the art. One method for preparing such copolymers useful in the present invention involves fitting a 3-necked 1 L flange flask with a mechanical stirrer, heating mantle, thermometer, reflux condenser, addition inlet, and provision for maintaining an inert atmosphere within the reaction vessel, such as a nitrogen inlet. The flask is charged with three hundred thirty six (336) grams of isopropanol and one hundred twelve (112) grams of water. Heating is commenced under stirring and slow nitrogen sweep until a gentle reflux is achieved, at about 80 deg. Centigrade. A first stream comprising eighty (80) milliliters of a 5% aqueous sodium persulphate solution was slowly added to the contents of the refluxing contents of the flask simultaneously with a second stream comprising a liquid mixture of 70.4 grams of styrene and 105.4 grams of methacrylic acid, over the course of about 2 hours. Following the addition, the temperature was maintained at reflux for an additional 2 hours to ensure complete reaction. Then, an additional ten (10) milliliters of 22% sodium persulphate was added, and the temperature maintained at reflux for one additional hour to provide a styrene/methacrylic acid copolymer.

[0017] To prepare the sodium salt of the aforesaid polymer, the flask from the above was set up for distillation by affixing a head and condenser thereto. The flask is heated until the azeotrope of isopropanol and water begins to distill, and then two hundred thirteen (213) grams of a 23% (wt.) aqueous solution of sodium hydroxide is slowly added to the flask during the distillation at a rate which is approximately equal to the rate at which the azeotrope is being distilled. The temperature of the contents of the flask are monitored, and when the temperature reaches 100-105 deg., the flask is allowed to cool to 50 degrees centigrade and the pH is adjusted to a level between about 8 and 10 using aqueous NaOH, and to a total solids content of between about 30 and 35% (wt.) as determined by evaporation of all of the water from a sample of known weight and dividing the weight of the solids remaining by the total initial weight and converting to a percentage by multiplication by 100.

[0018] The above procedure affords an aqueous solution comprising the sodium salt of styrene/methacrylic acid copolymer, to which may be added a multivalent metal ion in order to afford a composition according to the invention which is useful as an anti-coagulation additive for pitch and resinous materials in paper mills and other systems.

[0019] Although the styrene/methacrylic acid ratio in the above preparatory method is about 40:60, copolymers of styrene and methacrylic acid having other ratios are also useful herein as the copolymer component from which an anti-coagulant additive may be formed. The copolymers having any content of styrene in the range of 10.0% to 45.0%, by weight based upon the total weight of the styrene/methacrylic acid polymer, including every hundredth percentage therebetween, are suitable for use in the present invention. These polymers having varied amounts of styrene and methacrylic acid are made by altering the relative amounts of each of the components in the second stream referred to in the preparatory method above. For example, when a copolymer having a styrene to methacrylic acid ratio of: 30:70 is desired, the second stream comprises 52.70 grams of styrene and 123.06 grams of methacrylic acid. When a copolymer having a styrene to methacrylic acid ratio of 20:80 is desired, the second stream comprises 35.15 grams of styrene and 140.61 grams of methacrylic acid.

[0020] Although the water-soluble salt of the copolymer whose preparation is described above as being the sodium salt as formed by the addition of aqueous sodium hydroxide in the final step in which the alcohol is removed by distillation, other basic substances which produce a water-soluble polymer are suitable as employment as neutralizing agents herein. Such basic substances include without limitation alkaline aqueous solutions or suspensions of other soluble metal cations, metal oxides, carbonates, etc., including without limitation, basic carbonates of any of the alkali metals or monovalent iron, the basic oxides of any of the alkali metals or monovalent iron, ammonia, or alkyl amines including primary, secondary and tertiary amines provided that a solution of the copolymer results after the admixture and heating. In cases where suspensions of oxides are used, a longer heating time may be necessary to effectuate solution, depending upon the particle size of the basic substance.

[0021] The final polymers produced according to a procedure such as that described above may have molecular weights of any molecular weight value in the range of about 1,000 to about 100,000, with molecular weights having any value in the range of 1,500 to 50,000 being preferred, with molecular weights having any value in the range of about 2,000 to about 30,000 being most preferred.

[0022] The Multivalent Metal Component

[0023] Compositions prepared in accordance with and useful in the preferred form of the present invention are prepared from combining a solution of a copolymer component with a solution or suspension of a metal cation component. The multivalent metal component (or “metal cation” component) useful for admixture with the soluble copolymer component in accordance with the present invention may contain any metal cation which reduces the contact angle of the copolymer sufficiently to modify the surface of pitch, stickies, or the like from hydrophobic to hydrophilic. It is preferred that a multivalent cation used in the present invention is capable of existing and is present in a di-valent form. Thus, any metal for which stable divalent compounds are known to exist is suitable for use in the present invention. Such metals include, without limitation, magnesium, calcium, strontium, barium, nickel, copper, tin, cobalt, iron, and zinc. It is preferred that the multivalent metal is a divalent metal. It is more preferred that the multivalent metal is a metal selected from the group consisting of the alkaline earth metals. It is most preferred that the multivalent metal is selected from the group consisting of calcium and magnesium.

[0024] The Anti-Coagulant Compositions

[0025] Although a solution of a multivalent metal ion and a solution of a soluble copolymer of styrene and methacrylic acid may both be added separately to an aqueous system, it is preferred that these materials be mixed with one another prior to their being added to the system. This is because it is believed that the two species interact with one another to form an adduct or complex which possesses anti-coagulant properties for resin, pitch, lignin, and other bodies present in these aqueous systems. The present invention is concerned with preventing the deposition of particles derived from lignin, pitch, resin, and the like onto various articles and pieces of process equipment and these terms are intended herein to refer to any material which can be considered to form a sticky residue including without limitation: natural resins (fatty and resin acids, fatty esters, insoluble salts, sterols, etc.); defoamers (oil, EBS, silicate, silicone oils, ethoxylates); sizing agents (rosin size, ASA, AKD, hydrolysis products, insoluble salts); coating binders (PVAC, SBR); Waxes, Inks, Hot melt glues (EVA, PVAC, amorphous polyolefins); contact adhesives (SBR, vinyl acrylates, polyisoprene, and the like). From a physical standpoint, such deposits typically form from microscopic particles of materials having adhesive outer surfaces in the stock which accumulate on papermaking or pulping equipment. Such deposits are often found on stock chest walls, paper machine foils, Uhle boxes, paper machine wires, wet press felts, dryer felts, dryer cans, and calendar stacks. Such particles formed from resins, pitch, lignins and the like are usually particles of visible or nearly visible size.

[0026] To form a composition according to a preferred form of the invention, one begins with a first solution that contains a water soluble salt or solution of the copolymer, and a second solution that contains a soluble aqueous solution of the divalent metal selected. A vessel containing either of the solutions is caused to undergo agitation, and a stream of the second solution is slowly added to the first. Upon mixing of the two solutions, a clear solution is formed. It is this final clear solution that results from admixture of the soluble copolymer solution with a multivalent metal ion that is useful as an anti-coagulant in accordance with a preferred form of the present invention. Such a final solution containing an anti-coagulant may be simply added to the pulp mill's water system at any location which is upstream from the point where the pitch, resin, or lignin-derived material first comes into contact with calcium ions (typically from an outside water source used as rinse or process water) because calcium ions can react with pitch, resin, or lignin-derived material to form microscopic sized particulate precipitates, which particulate precipitates are capable of agglomerating with one another to form undesirable films and gummy precipitates.

[0027] As mentioned, the compositions of the present invention are effective at inhibiting the deposition of organic contaminants in all papermaking systems regardless of the type of process employed including without limitation kraft, acid sulfite, mechanical pulp and recycled fiber systems. Deposition in the brown stock washer, screen room, and Decker system in Kraft papermaking processes can be inhibited according to the teachings of the invention. The present compositions can be utilized to inhibit deposition on all surfaces of any papermaking system from the pulp mill to the reel of the paper machine, including those process contents having any pH in the range of about 3 to about 11, and under a variety of other system conditions including temperatures, ionic strengths, solids content, etc. More specifically, the styrene/methacrylic acid compositions effectively decrease the deposition not only on metal surfaces but also plastic and synthetic surfaces such as machine wires, felts, foils, Uhle boxes, rolls and headbox components. Further, the compositions of the present invention may be used with other pulp and papermaking additives including without limitation starches, whiteners such as titanium dioxide, defoamers, wet strength resins, sizing aids, and any other material known to those skilled in the art as being useful as a functional additive in a papermaking system.

[0028] The compositions of the present invention can be added to the paper-making system at any stage. They may be added directly to the pulp furnish or indirectly to the furnish through the headbox. In another form of the invention, an anti-coagulant composition prepared in accordance with the teachings herein may be sprayed directly onto pieces of equipment which are desired to be protected from the gummy precipitates or films. Also, a composition according to the invention may be sprayed onto areas upon which are already deposited gummy residues from pitch, resin, lignin, etc. Such areas may include without limitation wires, press felts, press rolls and other deposition-prone surfaces. When added by spraying techniques, the composition is preferably diluted with water to a satisfactory inhibitor concentration. Thus, a composition according to the invention may be added to any point in a pulp and papermaking system. Spraying may be conducted using a spray bar, atomizer, or other means known by those skilled in the art of providing a spray to a surface.

[0029] The compositions of the present invention can be added to the papermaking system neat, as a powder, slurry or in solution; the preferred primary solvent including without limitation, water. The compositions may be added specifically and only to a furnish identified as contaminated or may be added to blended pulps. The compositions may be added to the stock at any point prior to the manifestation of the deposition problem and at more than one site when more than one deposition site occurs. Combinations of the above additive methods may also be employed by feeding the pulp millstock, feeding to the paper machine furnish, and spraying on the wire and the felt simultaneously.

[0030] It is preferred that the weight ratio of styrene/methacrylic copolymer to multivalent cation in the complex formed according to the invention ranges from about 1:4 to about 1:500. More preferably, this ratio is in the range of between about 1:10 to about 1:400. It is most preferred that the weight ratio of styrene/methacrylic copolymer to multivalent cation in the complex formed according to the invention ranges from about 1:15 to about 1:300.

[0031] In use in an aqueous system in which there exist chemical species derived from resins, lignins, pitch, etc. which are capable of forming microscopic particles in the presence of calcium, which particles have a propensity to agglomerate to form an insoluble fouling, gummy film on plant equipment and the like, to which a composition according to the invention is to be added, the total concentration of the styrene/methacrylic acid copolymer present which is effective for preventing agglomeration of gummy residues on plant equipment and the like is between about 0.5 parts per million to 500 parts per million of styrene/methacrylic acid copolymer, based upon the weight of the pulp or solution to which a composition according to the invention is added. It is more preferred that this concentration is in the range of about 2.0 parts per million to 100 parts per million of styrene/methacrylic acid copolymer, based upon the weight of the pulp or solution. It is most preferred that the total concentration of copolymer present is in the range of between 5 and 80 parts per million based upon the weight of the pulp or solution to which it is added.

[0032] For purposes of the present invention, the term “an effective deposition inhibiting amount” is defined as that amount which is sufficient to inhibit deposition of residues derived from pitch, resin, lignin, and the like in pulp and papermaking systems. The effective amount to be added to the papermaking system depends on a number of variables including the pH of the system, hardness of the water, temperature of the water, additional additives, and the organic contaminant type and content of the pulp. Generally, from about 0.5 parts to about 150 parts of the inventive composition per million parts of pulp is added to the papermaking system. Preferably, from about 2 parts to about 100 parts of the inventive composition are added per million parts of pulp in the system.

[0033] The data set forth below were developed to evaluate test results obtained through use of the present invention. However, it quickly became evident that a synergistic result was discovered with respect to the contact angle measurements and the amount of calcium ion present. The following data are included as being illustrative of the present invention and should not be construed as being delimitive thereof in any way.

[0034] Surface Tension and Contact Angle Measurements

[0035] Contact angle measurements provide direct information about the hydrophobicity of a surface which is coated with a sticky substance, such as an agglomerated residue derived from a pitch, lignin, resin, etc. These measurements are thus capable of providing information about the change in the hydrophobicity of a surface as surface-active materials are adsorbed and/or de-sorbed at the surface. A lower contact angle indicates that the surface is less susceptible to deposition of such gummy residues. A zero contact angle is most preferred. Surface tension provides information about the surface activity of the surfactants. A lower surface tension indicates that the surfactant can emulsify and therefore stabilize the pitch dispersion more effectively. A stable dispersion will, in turn, minimize or prevent deposition.

[0036] A well-known Wilhelmy-type technique was used to obtain surface tensions and receding contact angles of a solid immersed in the solutions containing different treatments. The Kruss K-12 Tensiometer was used. The experiment was performed at room temperature (23.degree. C.). A clean platinum plate with exactly known geometry is brought in contact with liquid and the force acting on the plate is measured via a microbalance. The surface tension of the liquid is calculated from the measured force:

λ=P/(L×COS θ)

[0037] in which λ=surface tension; P=measured (Wilhelmy) force; and L=wetted length. In this equation, θ is the contact angle between the tangent at the wetting line and the plate surface. For the determination of the surface tension, the roughened and cleaned platinum plate is used and its contact angle is zero.

[0038] A packaging tape made from a styrenebutadiene rubber and vinylic esters and a polyester film such as MYLAR® (trademark of E. I. DuPont de Nemours), were used as a solid substrate for contact angle measurements. For the testing, a clean solid substrate was clamped on a film stage, then placed in a glass test cell. The test solution was added to the cell and the whole test cell was placed inside the chamber of a goniometer. The substrate was in contact with the solution for 30 minutes and after which an air bubble was positioned on the underside of the substrate with an inverted tip. Contact angle provides information about the hydrophobicity of a simulated surface comprising a pitch, resin, or lignin and the change in the hydrophobicity as surface-active materials are adsorbed and/or de-sorbed at the surface. A lower contact angle is indicative of the surface being less susceptible to stickies and/or pitch deposition. Surface tension provides information about the surface activity of the surfactants. A lower surface tension indicates that the surfactant is likely to adsorb at the contaminant's surface and thereby, stabilizing the pitch dispersion more effectively. A stable dispersion will minimize or prevent deposition. The results of this testing are reported in Table I. The following abbreviations are used in the examples which follow: STYMMA 1=styrene methacrylic copolymer (30 wt % styrene/70 wt % methacrylic acid); STYMMA 2=styrene methacrylic copolymer (10 wt % styrene/90 wt % methacrylic acid); STYMMA 3=styrene methacrylic copolymer (40 wt % styrene/60 wt % methacrylic acid); STYMAA 4=styrene methacrylic copolymer (50 wt % styrene/50 wt % methacrylic acid); STYMMA 5=styrene methacrylic copolymer (40 wt % styrene/60 wt % methacrylic acid but higher molecular weight than STYMMA 3); PVA=polyvinyl alcohol (88% hydrolysis); and DI H₂O=de-ionized water. TABLE I Surface Tension and Contact Angle Measurements at 23° C. of solutions having varied copolymer concentrations and calcium content in the complex. Surf. ID copolymer Ca Tension Contact Angle No. Substance level ppm ppm (dyne/cm) (degrees) 1 DI H₂O 0 0 72.8 63.2 (MYLAR ®) 70.9 (Tape) 2 DI H₂O + 0 50 72.8 63.2 (MYLAR ®) Ca 70.9 (Tape) 3 STYMMA 1 1 0 — 70.4 (Tape) 4 STYMMA 1 50 0 72.5 62.4 (MYLAR ®) 5 STYMMA 1 1000 0 — 56.8 (MYLAR ®) 6 STYMMA 1 0.5 50 — 41.2 (Tape) 7 STYMMA 1 1 50 — 32.4 (Tape) 8 STYMMA 1 10 50 54.6 21.6 (MYLAR ®) 9 STYMMA 1 50 50  50.23 13.1 (MYLAR ®) 10 STYMMA 3 1 50 — 26.0 (Tape) 11 PVA 1 0 — 51.9 (Tape) 12 PVA 3 0 — 45.9 (Tape)

[0039] The results presented in Table I demonstrate that the STYMMA polymers operate synergistically with calcium towards minimization of the contact angle. Contact angle measurements are shown in example 2, at 50 ppm calcium and in the absence of copolymer both substrates of Tape and MYLAR®. Looking at examples 3-5 shows the contact gle measurements for varying levels of copolymer but in the absence of calcium, and from the examples 2-5 it is clear that for both cases where copolymer is present in the absence of calcium and where calcium is present in the absence of copolymer, the magnitude of the contact angle measured is about the same in both cases, in the range of about 55-70 degrees. However, as is evident from the examples 6-10, when calcium and copolymer are both present, the contact angle drops dramatically, in evidence of the heretofore unknown synergy between styrene/methacrylic acid copolymers and calcium ion towards altering the hydrophobicity of a simulated surface comprising a pitch, resin, or lignin and the change in the hydrophobicity as surface-active materials are adsorbed and/or de-sorbed at the surface. The most dramatic effect is evident from comparing examples 9 and 4, which shows the dramatic effect of the presence of calcium on the decrease in the surface tension and contact angle.

[0040] Standard Tape Detackification Test

[0041] This test method measures the effect of chemical additives on contact adhesion. An adhesive tape (2″×4″) and a polyester coupon (2″×4″) were treated with the test solution (600 gram). The solution contained in a 600 mL beaker is placed in a water bath with agitation and heated to the desired temperature. After 30 minutes of immersion, the tape and coupon are removed from the solution and pressed to 10,000 lb force for 1 minute and then the peel force is then measured. A reduction of peel force indicates the level of detackification of the adhesive surface. The more the adhesive surface is detackified, the less the deposition potential of particulate residues derived from pitch, lignin, resin, etc. would be. The % control or detackification is calculated by the following equation:

%detackification=[(untreated force)−(treated force)]×100/untreated force

[0042] Results of this testing are set for the in Table II below: TABLE II Standard Tape Detackification Test Sam- Peel ple Dosage Ca Temp. Force % No. Substance (ppm) (ppm) ° C. (lbf) detackification 1 DI H₂O 0 50 5.13 0 2 STYMAA 1 0.15 0 50 4.50 2.2 3 STYMAA 1 0.15 5 50 4.00 13.0 4 STYMAA 1 0.15 10 50 1.07 76.7 5 STYMAA 1 0.15 30 50 0.59 87.2 6 STYMAA 1 0.15 50 50 0.28 94.5 7 STYMMA 1 0.15 100 50 0.20 95.7 8 STYMMA 1 0.15 500 50 0.31 93.3 9 STYMAA 1 0.10 100 50 0.93 79.8 10 STYMAA 1 0.25 100 50 0.03 99.3 11 DI H₂O 0 0 25 6.1 0 12 STYMAA 1 0.25 0 25 6.02 0 13 STYMAA 1 0.25 10 25 3.40 33.7 14 STYMAA 1 0.25 30 25 2.00 61.0 15 STYMAA 1 0.25 50 25 1.77 65.5 16 STYMAA 1 0.25 100 25 0.68 86.7 17 STYMAA 1 0.25 200 25 0.52 89.9 18 STYMAA 1 0.25 500 25 0.36 93.0 19 PVA 1 25 0.63 87.7 20 STYMAA 3 0.15 50 50 0.34 93.4 21 STYMAA 5 0.15 50 50 1.58 69.2 22 STYMAA 4 0.15 50 50 3.57 43.7 23 STYMAA 2 0.15 50 50 1.56 69.6

[0043] These results confirm the results set forth in Table I that the efficacy of styrene methacrylic acid copolymers towards inhibiting deposition of the residues addressed herein is significantly increased when it is used together with multivalent metallic species such as calcium ions. From In examples 2-8 it is clear that increasing the calcium increases the detackification values. Increased detackification occurs upon increasing the calcium concentration to about 50 ppm, after which the performance levels are seen to level off. Examples 11-18 evidence the same performance qualities of the compositions, except at lower temperature, thus evidencing the temperature-independence of the general effect discovered. In addition, there seems to be an optimum styrene content as evidenced by examples 20-23, which is about 15% to about 40%. Of the styrene methacrylic copolymers tested, STYMAA 1 and STYMMA 3 exhibited the best performance as reflected by their ultra-low peel force. These results are in agreement with those obtained from surface tension and contact angle measurements. Thus these are preferred polymer compositions according to the invention.

[0044] Consideration must be given to the fact that although this invention has been described and disclosed in relation to certain preferred embodiments, obvious equivalent modifications and alterations thereof will become apparent to one of ordinary skill in this art upon reading and understanding this specification and the claims appended hereto. Accordingly, the presently disclosed invention is intended to cover all such modifications and alterations, and is limited only by the scope of the claims which follow. 

I claim: 1) An aqueous composition of matter which comprises: a) a copolymer component comprising a water soluble anionic form of styrene/methacrylic acid copolymer in which the copolymer has a styrene content in the range of 10.0% to 45.0% by weight based upon the total weight of the styrene/methacrylic acid copolymer, including every hundredth percentage therebetween, and wherein said copolymer component has a molecular weight in the range of 2,000 to 30,000 including every molecular weight therebetween; and b) a metal component comprising an aqueous solution containing at least one multivalent cation selected from the group consisting of: calcium, magnesium, strontium, barium, nickel, copper, tin, cobalt, iron, zinc, or mixtures thereof, wherein the ratio of the copolymer component to the metal component is in the range of between 1:4 to 1:500 on a weight basis. 2) A composition according to claim 1 wherein the ratio of the copolymer component to the metal component is in the range of between 1:10 to 1:400 on a weight basis. 3) A composition according to claim 1 wherein the ratio of the copolymer component to the metal component is in the range of between 1:15 to 1:300 on a weight basis. 4) A composition according to claim 1 wherein said copolymer component has a styrene content in the range of 15.0% to 38.0% by weight based upon the total weight of the styrene/methacrylic acid polymer, including every hundredth percentage therebetween. 5) A composition according to claim 1 wherein said copolymer component has a molecular weight in the range of 5,000 to 25,000 including every molecular weight therebetween. 6) An aqueous composition of matter which comprises: a) a copolymer component comprising a water soluble anionic form of styrene/methacrylic acid copolymer in which the copolymer has a molecular weight in the range of 2,000 to 30,000 including every molecular weight therebetween; and b) a metal component comprising an aqueous solution containing at least one multivalent cation selected from the group consisting of: calcium, magnesium, strontium, barium, nickel, copper, tin, cobalt, iron, zinc or mixtures thereof, wherein the ratio of the copolymer component to the metal component is in the range of between 1:4 to 1:500 on a weight basis. 7) A composition according to claim 6 wherein the ratio of the copolymer component to the metal component is in the range of between 1:10 to 1:400 on a weight basis. 8) A composition according to claim 6 wherein the ratio of the copolymer component to the metal component is in the range of between 1:15 to 1:300 on a weight basis. 9) A composition according to claim 6 wherein the molecular weight of the copolymer is in the range of 5,000 to 24,000, including every molecular weight therebetween. 10) A composition according to claim 6 wherein the molecular weight of the copolymer is in the range of 9,000 to 18,000, including every molecular weight therebetween. 11) A composition according to claim 6 wherein the molecular weight of the copolymer is in the range of 11,000 to 15,000, including every molecular weight therebetween. 12) An aqueous composition of matter which comprises: a) a copolymer component comprising a water soluble form anionic of styrene/methacrylic acid copolymer in which the copolymer has a styrene content in the range of 10.0% to 45.0% by weight based upon the total weight of the styrene/methacrylic acid copolymer, including every hundredth percentage therebetween; and b) a metal component comprising an aqueous solution containing at least one multivalent cation selected from the group consisting of: calcium, magnesium, strontium, barium, nickel, copper, tin, cobalt, iron, zinc, or mixtures thereof, wherein the ratio of the copolymer component to the metal component is in the range of between 1:4 to 1:500 on a weight basis. 13) A composition according to claim 12 in which the styrene content of the copolymer is in the range of between about 15.0% and 35.0%, by weight based upon the total weight of the styrene/methacrylic acid copolymer, including every hundredth percentage therebetween. 14) A composition according to claim 12 in which the styrene content of the copolymer is in the range of between about 18.0% and 30.0%, by weight based upon the total weight of the styrene/methacrylic acid copolymer, including every hundredth percentage therebetween. 15) A composition according to claim 12 in which the styrene content of the copolymer is in the range of between about 21.0% and 27.0%, by weight based upon the total weight of the styrene/methacrylic acid copolymer, including every hundredth percentage therebetween. 16) A process for preventing deposition of pitch, resin, stickies, lignin, and other residues on processing equipment in processes in that such species are present which comprises the steps of: a) providing an aqueous composition of matter which comprises: i) a copolymer component comprising a water soluble anionic form of styrene/methacrylic acid copolymer; and ii) a metal component comprising an aqueous solution containing at least one multivalent cation selected from the group consisting of: calcium, magnesium, strontium, barium, nickel, copper, tin, cobalt, iron, zinc, or mixtures thereof; and b) introducing an effective deposition inhibiting amount of said aqueous composition into a process stream in which pitch, resin, lignin, and other residues are liberated, wherein the concentration of the copolymer component of said aqueous composition in said process stream is in the range of between 0.5 parts per million to 500 parts per million by weight based upon the weight of said process stream. 17) A process according to claim 16 wherein the concentration of the copolymer component of said aqueous composition in said process stream is in the range of between 2.0 parts per million to 150 parts per million by weight based upon the weight of the process stream 18) A process as in claim 16 wherein the metal component is present in said process stream in any amount between 4 times the amount of the copolymer component and 500 times the amount of the copolymer component. 19) A process as in claim 17 wherein the metal component is present in said process stream in any amount between 4 times the amount of the copolymer component and 500 times the amount of the copolymer component. 20) A process according to claim 16 wherein said multivalent cation is selected from the group consisting of: calcium and magnesium; and wherein the molecular weight of the copolymer is in the range of 2,000 to 30,000 including every molecular weight therebetween 